Intersection Median Barriers

Median barriers, also called median diverters or island diverters, are raised islands located in the center of an intersection where a minor (local) street intersects a major (main) street; they are used to restrict left turn and cross-street movements of motor vehicle traffic at the minor street to reduce cut-through routes in local neighborhoods. Median islands should always provide bicycle and pedestrian access. Appropriate regulatory and warning signage should be provided to alert users of changes in the roadway.

Purpose

Where it is desired to reduce cut-through traffic on neighborhood streets, intersection median barriers are used to restrict motor vehicle access for left-turn and cross-street through movements. Median barriers can enhance the comfort and accessibility of a street for pedestrians and bicyclists by reducing traffic volumes, preventing turning conflicts, and reducing pedestrian crossing distances and exposure to motor vehicles when pedestrian crossing islands/refuges are incorporated.

Considerations

• Intersection median barriers should only be considered as part of an overall traffic calming strategy. Traffic patterns should be analyzed to ensure that cut-through traffic will not be diverted to a nearby local street and that local residents do not have to drive excessive distances to access their homes.
• If designed as a crossing island, the median must be at a minimum 6 feet wide to provide at-grade accessible cut-throughs with tactile warning strips.
• Median barriers require strong support from the local community, and a highly interactive public process should be conducted before installation.
• Consideration must be given to the impact of median islands on emergency vehicles; designs should be coordinated with a local emergency response program. Some designs (e.g. mountable curbs) may allow fire truck access while inhibiting cars.3,4